Assyrians in Iran (Persian: آشوریان در ایران‎), or Iranian Assyrians, are an ethnoreligious and linguistic minority in present-day Iran. The Assyrians of Iran are a Semitic people who speak modern Assyrian, a neo-Aramaic language descended from Classical Syriac and elements of Akkadian, and are Eastern Rite Christians belonging mostly to the Assyrian Church of the East and, to a lesser extent, to the Chaldean Catholic Church. They share a common identity, rooted in shared linguistic and religious traditions, with Assyrians in Iraq and elsewhere in the Middle East, as well as with the Assyrian diaspora.

The Assyrian community in Iran numbered approximately 200,000 prior to the Islamic Revolution of 1979. However, after the revolution many Assyrians left the country, primarily for the United States, and the 1996 census counted only 32,000 Assyrians. Current estimates of the Assyrian population in Iran range from 32,000 (as of 2005) to 50,000 (as of 2007). The Iranian capital, Tehran, is home to the majority of Iranian Assyrians; however, approximately 15,000 Assyrians reside in northern Iran, in Urmia and various Assyrian villages in the surrounding area.

There were about 200,000 Assyrians in Iran at the time of the 1976 census. Many emigrated after the revolution in 1979, but at least 50,000 were estimated to be still in Iran in 1987.

Assyrians have a long history in Iran. During the Neo-Assyrian Empire (911–608 BC), much of western Iran (including Medes, Persia, Elam and Gutium) was subject to Assyria. After the fall of the Assyrian Empire, Assyria was ruled by Persia from 539 BC. Assyrians have possibly existed in north-western Iran for many thousands of years.

The traditional home of the Assyrians in Iran is along the western shore of Lake Urmia from the Salmas area to the Urmia plain. During the Assyrian Genocide, which took place in World War I, the Ottoman Army and Kurdish tribes along the Iranian-Turkish border carried out massacres and deportations on the Assyrians both in the mountains and on the rich plains, resulting in the death of 300,000 Assyrians. In 1914 alone, they attacked dozens of villages and drove off all the inhabitants of the district of Gawar. The Assyrians armed themselves and for a time successfully repelled further attacks under the leadership of Agha Petros, seizing control of much of the Urmia region and defeating Ottoman forces and their Kurdish and Azeri allies. However lack of ammunition and supplies, due mainly to the withdrawal of Russia from the war, and the collapse of allied Armenian forces led to their downfall. Massively outnumbered, surrounded, undersupplied and cut off, the Assyrians suffered terrible massacres. By the summer of 1918 almost all surviving Assyrians had fled to Tehran or refugee camps in Iraq. Local Kurds and Turks (Azari) took the opportunity of the last phases of World War I to rob Assyrian homes, carry off young women, and leave those remaining destitute. The critical murder that sowed panic in the Assyrian community came when Kurdish militias, under Agha Ismail Simko, assassinated the Patriarch, Mar Benyamin Shimon XXI, on March 3, 1918, under the pretext of inviting him to negotiations.